Hydrostatic Pressure Enhances Chondrogenic Differentiation of Mesenchymal Stem Cells in Silk Fibroin-Based 3D Bioprinted Hydrogels

The human meniscus experiences mechanical forces and converts axial loads into hoop stresses. Meniscus injuries and meniscectomies can compromise this function, and therefore, meniscus implants are required. To assess their performance in vitro, it is crucial to recreate a physiological environment. Therefore, we investigated the effect of TGFβ-3-supplemented and TGFβ-free cyclic hydrostatic pressure (HP) up to 10 MPa on 3D bioprinted silk fibroin (SF) polymer-based hydrogels. The bioink was seeded with human infrapatellar fat pad-derived MSCs and supplemented with an extracellular matrix and gelatin. We found that HP stimulation did not alter cell-free biomaterial maturation, while it partially stimulated metabolic activity and cell proliferation. Remarkably, TGFβ-3-supplemented HP led to the highest expression levels of chondrogenic markers, followed by TGFβ-3-supplemented unloaded incubation and then TGFβ-free HP. Despite the low cell density, the combined exposure to TGFβ-3 and HP also facilitated localized glycosaminoglycan and collagen deposition, demonstrating promising prospects for future meniscus regeneration.